In communication devices employing an adaptive array antenna, a transmission system is provided for each of the antennas, and a difference in transmission characteristic between these transmission systems affect on the entire transmission characteristic. Accordingly, in order to reduce the effect, used is transmission calibration weight indicating the difference in transmission characteristic between the transmission systems. In the technique disclosed in Japanese Patent Application Publication 2005-348236, transmission calibration weight is calculated in the following manner. A communication device sequentially sends calibration signals to respective transmission systems. A calibration terminal receives the calibration signals thus sent, and calculates transmission system characteristic data indicating the characteristic of each calibration signal. This transmission system characteristic data show the transmission characteristic of each transmission system. The communication device calculates transmission calibration weight on the basis of the difference between the transmission systems in the transmission system characteristic data.